BUILD STRENGTH, BALANCE & COORDINATION: Toning Exercise Balls are ideal for balance, flexibility & strength workouts. Performing exercises with this small weight ball engages your bodys deepest stabilizing muscles for coordination & maximized strength PVC SHELL UNSTABLE IRON SAND INSIDE: Made of PVC and filled with iron sand, our weighted balls for exercise are durable to function well for a lifetime. Iron sand inside creates instability to activate different muscle groups for a leaner & tighter body COMPACT AND PORTABLE: Take this small exercise ball or hand exercise ball on your travels for a quick workout. Keep it at the office to stretch and warm up your muscles with a weighted ball during breaks or after a long day at your desk. MAKE SURE TO CHOOSE THE APPROPRIATE WEIGHT: Please check these hand exercise balls s size carefully to see whether it fits your hands or not before purchase (for the larger size, you might need to hold it with both hands). VERSA